// Copyright (c) 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "cc/test/pixel_comparator.h"

#include <stdint.h>

#include <algorithm>

#include "base/logging.h"
#include "ui/gfx/geometry/rect.h"

namespace cc {

ExactPixelComparator::ExactPixelComparator(const bool discard_alpha)
    : discard_alpha_(discard_alpha)
{
}

bool ExactPixelComparator::Compare(const SkBitmap& actual_bmp,
    const SkBitmap& expected_bmp) const
{
    // Number of pixels with an error
    int error_pixels_count = 0;

    gfx::Rect error_bounding_rect = gfx::Rect();

    // Check that bitmaps have identical dimensions.
    DCHECK(actual_bmp.width() == expected_bmp.width() && actual_bmp.height() == expected_bmp.height());

    SkAutoLockPixels lock_actual_bmp(actual_bmp);
    SkAutoLockPixels lock_expected_bmp(expected_bmp);

    for (int x = 0; x < actual_bmp.width(); ++x) {
        for (int y = 0; y < actual_bmp.height(); ++y) {
            SkColor actual_color = actual_bmp.getColor(x, y);
            SkColor expected_color = expected_bmp.getColor(x, y);
            if (discard_alpha_) {
                actual_color = SkColorSetA(actual_color, 0);
                expected_color = SkColorSetA(expected_color, 0);
            }
            if (actual_color != expected_color) {
                ++error_pixels_count;
                error_bounding_rect.Union(gfx::Rect(x, y, 1, 1));
            }
        }
    }

    if (error_pixels_count != 0) {
        LOG(ERROR) << "Number of pixel with an error: " << error_pixels_count;
        LOG(ERROR) << "Error Bounding Box : " << error_bounding_rect.ToString();
        return false;
    }

    return true;
}

FuzzyPixelComparator::FuzzyPixelComparator(
    const bool discard_alpha,
    const float error_pixels_percentage_limit,
    const float small_error_pixels_percentage_limit,
    const float avg_abs_error_limit,
    const int max_abs_error_limit,
    const int small_error_threshold)
    : discard_alpha_(discard_alpha)
    , error_pixels_percentage_limit_(error_pixels_percentage_limit)
    , small_error_pixels_percentage_limit_(small_error_pixels_percentage_limit)
    , avg_abs_error_limit_(avg_abs_error_limit)
    , max_abs_error_limit_(max_abs_error_limit)
    , small_error_threshold_(small_error_threshold)
{
}

bool FuzzyPixelComparator::Compare(const SkBitmap& actual_bmp,
    const SkBitmap& expected_bmp) const
{
    // Number of pixels with an error
    int error_pixels_count = 0;
    // Number of pixels with a small error
    int small_error_pixels_count = 0;
    // The per channel sums of absolute errors over all pixels.
    int64_t sum_abs_error_r = 0;
    int64_t sum_abs_error_g = 0;
    int64_t sum_abs_error_b = 0;
    int64_t sum_abs_error_a = 0;
    // The per channel maximum absolute errors over all pixels.
    int max_abs_error_r = 0;
    int max_abs_error_g = 0;
    int max_abs_error_b = 0;
    int max_abs_error_a = 0;

    gfx::Rect error_bounding_rect = gfx::Rect();

    // Check that bitmaps have identical dimensions.
    DCHECK(actual_bmp.width() == expected_bmp.width() && actual_bmp.height() == expected_bmp.height());

    // Check that bitmaps are not empty.
    DCHECK(actual_bmp.width() > 0 && actual_bmp.height() > 0);

    SkAutoLockPixels lock_actual_bmp(actual_bmp);
    SkAutoLockPixels lock_expected_bmp(expected_bmp);

    for (int x = 0; x < actual_bmp.width(); ++x) {
        for (int y = 0; y < actual_bmp.height(); ++y) {
            SkColor actual_color = actual_bmp.getColor(x, y);
            SkColor expected_color = expected_bmp.getColor(x, y);
            if (discard_alpha_) {
                actual_color = SkColorSetA(actual_color, 0);
                expected_color = SkColorSetA(expected_color, 0);
            }

            if (actual_color != expected_color) {
                ++error_pixels_count;

                // Compute per channel errors
                int error_r = SkColorGetR(actual_color) - SkColorGetR(expected_color);
                int error_g = SkColorGetG(actual_color) - SkColorGetG(expected_color);
                int error_b = SkColorGetB(actual_color) - SkColorGetB(expected_color);
                int error_a = SkColorGetA(actual_color) - SkColorGetA(expected_color);
                int abs_error_r = std::abs(error_r);
                int abs_error_g = std::abs(error_g);
                int abs_error_b = std::abs(error_b);
                int abs_error_a = std::abs(error_a);

                // Increment small error counter if error is below threshold
                if (abs_error_r <= small_error_threshold_ && abs_error_g <= small_error_threshold_ && abs_error_b <= small_error_threshold_ && abs_error_a <= small_error_threshold_)
                    ++small_error_pixels_count;

                // Update per channel maximum absolute errors
                max_abs_error_r = std::max(max_abs_error_r, abs_error_r);
                max_abs_error_g = std::max(max_abs_error_g, abs_error_g);
                max_abs_error_b = std::max(max_abs_error_b, abs_error_b);
                max_abs_error_a = std::max(max_abs_error_a, abs_error_a);

                // Update per channel absolute error sums
                sum_abs_error_r += abs_error_r;
                sum_abs_error_g += abs_error_g;
                sum_abs_error_b += abs_error_b;
                sum_abs_error_a += abs_error_a;
            }
        }
    }

    // Compute error metrics from collected data
    int pixels_count = actual_bmp.width() * actual_bmp.height();
    float error_pixels_percentage = 0.0f;
    float small_error_pixels_percentage = 0.0f;
    if (pixels_count > 0) {
        error_pixels_percentage = static_cast<float>(error_pixels_count) / pixels_count * 100.0f;
        small_error_pixels_percentage = static_cast<float>(small_error_pixels_count) / pixels_count * 100.0f;
    }
    float avg_abs_error_r = 0.0f;
    float avg_abs_error_g = 0.0f;
    float avg_abs_error_b = 0.0f;
    float avg_abs_error_a = 0.0f;
    if (error_pixels_count > 0) {
        avg_abs_error_r = static_cast<float>(sum_abs_error_r) / error_pixels_count;
        avg_abs_error_g = static_cast<float>(sum_abs_error_g) / error_pixels_count;
        avg_abs_error_b = static_cast<float>(sum_abs_error_b) / error_pixels_count;
        avg_abs_error_a = static_cast<float>(sum_abs_error_a) / error_pixels_count;
    }

    if (error_pixels_percentage > error_pixels_percentage_limit_ || small_error_pixels_percentage > small_error_pixels_percentage_limit_ || avg_abs_error_r > avg_abs_error_limit_ || avg_abs_error_g > avg_abs_error_limit_ || avg_abs_error_b > avg_abs_error_limit_ || avg_abs_error_a > avg_abs_error_limit_ || max_abs_error_r > max_abs_error_limit_ || max_abs_error_g > max_abs_error_limit_ || max_abs_error_b > max_abs_error_limit_ || max_abs_error_a > max_abs_error_limit_) {
        LOG(ERROR) << "Percentage of pixels with an error: "
                   << error_pixels_percentage;
        LOG(ERROR) << "Percentage of pixels with errors not greater than "
                   << small_error_threshold_ << ": "
                   << small_error_pixels_percentage;
        LOG(ERROR) << "Average absolute error (excluding identical pixels): "
                   << "R=" << avg_abs_error_r << " "
                   << "G=" << avg_abs_error_g << " "
                   << "B=" << avg_abs_error_b << " "
                   << "A=" << avg_abs_error_a;
        LOG(ERROR) << "Largest absolute error: "
                   << "R=" << max_abs_error_r << " "
                   << "G=" << max_abs_error_g << " "
                   << "B=" << max_abs_error_b << " "
                   << "A=" << max_abs_error_a;

        for (int x = 0; x < actual_bmp.width(); ++x) {
            for (int y = 0; y < actual_bmp.height(); ++y) {
                SkColor actual_color = actual_bmp.getColor(x, y);
                SkColor expected_color = expected_bmp.getColor(x, y);
                if (discard_alpha_) {
                    actual_color = SkColorSetA(actual_color, 0);
                    expected_color = SkColorSetA(expected_color, 0);
                }
                if (actual_color != expected_color)
                    error_bounding_rect.Union(gfx::Rect(x, y, 1, 1));
            }
        }
        LOG(ERROR) << "Error Bounding Box : " << error_bounding_rect.ToString();
        return false;
    } else {
        return true;
    }
}

} // namespace cc
